Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.
Both bricks and blocks are great building materials. They both have great compressive strength, resistance to fire, and offer different degrees of insulation. For this reason, they are often used in combination. To determine whether one is better than the other, will solely depend on what project you are preparing and what features matter the most to you.
For a general structural building, brick is going to be an excellent choice for fire resistance, low maintenance, and overall durability in comparison to blocks. When it comes down to strength, environmental relationship, and costs, bricks and blocks are quite comparable.
Let’s explore the different characteristics and where brick and blocks stand in each comparison. It’s not always a black and white comparison and not one type of material always wins the category in all circumstances.
Let’s start with composition. What is the main difference between brick and block?
Red or clay bricks are traditional building material made from natural resources. Bricks are generally a mixture of sand, lime, and concrete materials. There are also traces of barium (Ba), Manganese (Mn), and other constituents that are added when combining minerals during the clay creation.
Different elements can help with different types and colors of brick, but barium carbonate is an added constituent to enhance the brick’s resistance to natural elements and attack on brick.
What kind of blocks? Concrete blocks?
To clarify what blocks are, it is important to note that there are several styles of blocks that fall under the category.
In general, all concrete blocks are made with cement, water, and aggregates. Aggregates can sand or alternatives. A chemical reaction occurs during the combination which provides the strong bonds between the elements that offer the high strength.
There are different types of concrete blocks used in construction. Here is a quick list to review the different types of blocks you will encounter when finding a building material. Note that these are all under the same category, “concrete block”
- Concrete stretcher, corner, and pillar blocks
- Jamb concrete blocks
- Partition concrete blocks
- Lintel blocks
- Bull nose block
(source: The Constructor)
Additionally, when you encounter concrete blocks, you will see the different ways they are labeled. Concrete block masonry (CMU) commonly come in 2-, 4-, 6-, 8-, 10-, and 12- unit configurations which just identifies the units in “inches,”
Two types of concrete blocks and bricks exist. Both blocks and bricks have hollow cavities which can be favorable in some conditions, for example, air can provide insulation while keeping the units lightweight.
Below list overviews the main differences between solid and hollow units. Unless specified otherwise, the characteristics represent both brick and block units in either solid or hollow forms.
- Solid concrete blocks are heavy in weight and manufactured from dense aggregates.
- Generally strong and stable
- Great for large work that require load bearing walls
- Void areas can range, but are usually greater than 25%
- Solid areas are greater than 50%
- Generally made of lightweight aggregates for concrete blocks
- Easy installation and lightweight in comparison to solid forms
- To keep the blocks or bricks stacked, they are held together by concrete mortar
- Light and rather economical
Overall a hollow cement also provides additional perks in its natural characteristics. In addition to its low maintenance and fire-resistant features (will discuss further in the next few sections), The hollow style of the block provides insulation which helps to keep hot or cold air outside of the house/unit.
Both concrete blocks and clay bricks are used for load-bearing walls and therefore strength is an important factor to consider when it comes to selecting material. This includes shearing stress, flexural stress, and compressive strength.
All building materials are regulated to a standard, ASTM C90. For example, per ASTM C 90-91 – compression strength is defined at a minimum value and the overall void area and face shell (minimum) in a block unit is governed.
It is important to note that all strength evaluations are important in determining the full strength and functionality of a block than the commonly mentioned compressive strength.
Although it may feel like overkill when considering building material in places with massive ground movements, heavy floods, and heavy wind, it is important to consider all strengths such as compressive and flexural bending, along with shear strength of masonry.
Most importantly, many researches in science and engineering for construction material consider these elements as key factors in understanding the right material.
The following values of strength are based on a research study which was specifically focused on studying the impact of hollow cement and the effect on water absorption, compressive strength, compressive, shear, and flexural tensile strength that void size can have.
To review terms of the research the following is defined. Void areas are the hollow areas of the block. The gross area is the general Length (L) x Width (W) of the cement block while the net area was L x W of the remaining areas after subtracting the void areas from the gross area.
In this particular study, the author measured the mechanical performance of various blocks with different void areas. Per ASTM C90, concrete blocks and bricks must have a minimum of 1900psi.
In general, amongst the various types of blocks, the average concrete block can withstand roughly 3500 psi. As for an average clay (red) brick, these units can withstand up to 3000 psi.
In this research, solid brick was used, and the gross strength on it was roughly 2.15MPa. This was a base line used to compare the strengths of blocks but also the changes in strength on this cement block when voids are increased.
- When void increased (0 to 44% observed), the general gross strength significantly decreased. (4.96 MPa to 1.00 MPa in reference experiment).
- The brick’s gross strength, 2.15MPa was comparable to a cement block with roughly 24% void area. Meaning, cement blocks with 0-16% void performed better gross strength in comparison to brick while the cement blocks with void areas greater than 24% performed worse than a solid brick.
A Win for the Blocks
An important conclusion in this experiment was that cement block with 0 void in comparison to a brick, had significantly higher compression strength at 4.96 MPa compared to 2.15 respectively. The cement block outperformed the brick until there was a void of close to 24%.
Masonry Shear Strength and Flexural Tensile Strength
Although there aren’t direct relationships of block to brick for shear strength and flexural strength in the experiment we are referencing, I thought it was important to visit these two variables.
For the reference experiment, shear strength was calculated using the following
Shear Strength= P+W2A
Where P was the ultimate load, in which the load was applied under displacement control.
W, the weight of the cement block, and A is the area of the failure surface.
For the gross strength, the void ratio, which increased from a solid brick to 40%, was inversely related to shear strength and decreased roughly 40%.
Although this is not a direct comparison, an alternative study was performed for studying shear stress on brick and brickwork.
In this study, shear stress was by clamping a brick between two steel plates in a test rig. The shear force applied to a quarter of the brick that was cantilevered from the steel. In comparison, the experiment above was applied to a zero axial pre-compression load which was applied under displacement control.
Although various bricks were studied, the shear stress on a single brick, single shear test ranged from a mean of 1.06 N/mm2 (1.06 MPa) to 6.33 N/mm2 (6.33 MPa).
(Source: The Shear Strength of Bricks and BrickWork)
For flexural strength, as the void area ratio increased from 0 to 16%, the flexural tensile strength reduced by 36%. For 16% and above (44%), the flexural strength further reduced, yet at a lower rate, but an additional 24%.
Concrete masonry is known for its non-combustible characteristic. For this characteristic, the researchers observed the hours of fire resistance in comparison to the void percentage.
The thickness of the masonry which is calculated by taking the net volume of the unit and dividing it by the product of the length and height of the masonry, was compared to the general fire resistance per hour. From the simple calculation, hours of fire resistance decreased as the thickness decreased.
As thickness decreased from the control, 115mm to 65mm, the hours of fire resistance decreased from 3.0 to 1.0 hours, respectively.
Unlike aerated blocks, bricks are generally fire-resistance and more susceptible to burning due to its compressed characteristic. Although aeration will depend on the type of block you are looking at, in comparison to a compressed earthen material the bricks offer, it falls short to fire resistance.
The extremely compact and compress feature gives little space for combustion or ignition within a brick. Brick has the highest fire rating and can sustain fire accidents better than blocks or other building materials.
The results can be visited here: Effect of Void Area on Hollow Cement Masonry Mechanical Performance.
A Win For The Bricks
Bricks are generally very durable and low maintenance. When a building or structure is built properly with good skills and paired with durable construction material, they will remain strong and stiff throughout the years without much maintenance.
A Win for the Bricks.
As will be mentioned previously and in the later section, “environmental impact,” bricks are a great building material that does not require much maintenance, in fact they are almost free of maintenance. Once structures are constructed with bricks, they do not require the regular maintenance.
As for blocks, they generally need some TLC after a few years to prevent falling apart.
In construction, R-value is an important measurement of the build material’s (or insulation’s) heat flow resistance. The R-value expresses the temperature difference that will effect one unit of area.
|Concrete Masonry Unit (4”)||0.80|
|Concrete block (8”)||1.9-2.5|
R-value is from this list of R-value of Building Materials
Furthermore, this is a comparison of insulation values for different blocks in units of W/mK.
|Type of block||R-value|
|Honeycomb clay block||0.10 W/mK|
|Hemp Block||0.11 W/mK|
|Unfired Clay block||0.21-0.95 W/mK|
|Insulated concrete form block||0.083 W/mK|
Source: Blocks and its alternatives.
General brick walls have an R value of 0.2 per square inch, while a 8” concrete block offers an R-value of 0.08 per square inch, which results in the R-value of 2.5 in a full block.
Keep in mind that insulation values are additive. If you also add insulation to your walls, for example, to concrete blocks, the R-value can increase to 1.2 per square inch (in the given example).
Yet, it is important to note that not just the insulation value determines whether or not It’s the optimum selection to keep hot air in or out. In fact, the insulation value could also be deceiving for sound proofing.
Consider the situations below and see which option best suits your project. Is it heat that you are concerned with? Are you located in a busy city center?
A Win for the Bricks
Are you in a hot dessert zone? Do you need to keep heat out majority of the time?
A significant “win” for the bricks on this subject. Bricks are able to absorb heat energy from the sun during the day while it insulates the home. They have been loved for a long time for this characteristic. It’s beneficial for hot zones and reversely, great for cold nights.
This characteristic is called (high) thermal mass. Since brick units are able absorb more heat during the day in comparison to blocks, they are able to keep homes warm in the cooler evenings and cool in the summer’s hot afternoon.
This heat is stored then released during the evening which makes it a great feature for buildings and home structures in high temperature areas.
A Win for the Blocks
If you are dealing with a busy city, you may select blocks instead. For sound insulation, blocks are a great method to soundproof your structure. For areas with high traffic and sound pollution, block walls can offer the far superior soundproofing feature due to its cement components.
They are higher density in overall unit offers the higher soundproof which is a great feature for homes near a railway, airport, or busy roads.
Additionally, a concrete block with air-entrainment can have an R-value up to 3.9 thanks to the air bubbles providing insulation.
Cost may be comparable per unit, but it is important to consider how the cost adds up with the way it is sold and the labor cost.
For example, brick units are sold by the thousand while mortar is sold by the box. Masonry labor is generally charged by the thousand. The main differences divide at a measurement that most architects and builders will consider, the resulting square footage.
In most cases, bricks are smaller than the conventional block size. Whether it’s a comparison between different brick sizes (king size brick vs. modular size bricks), or a comparison between brick installations and block installation, the larger units are more cost efficient for installation in general.
Most installations tend to be cheaper whether its brick or cement block applications.
A win for the blocks
Due to the general shape and size of blocks, they are known to cost less than bricks when it comes to square footage. In addition to the lesser cost of material, they are also easy to make.
The cheap and feasible manufacturing offers an additional cost reduction option. Some builders use this opportunity by producing the blocks on site of the build. This saves costs for transport, structural integrity, and also the hassle.
With many builders and architects becoming more environmentally “green,” they encounter challenging circumstances for building especially when it comes to importing and general transportation of material. This is an alternative some builders use to overcome some challenges.
In general, red bricks are generally labeled as unfriendly to the environment. The main reason being, red bricks are banned from being dug up without prior environment clearance ever since the National Green Tribunal took action.
The National Green Tribunal took action for good reason. As mentioned in the composition section, clay bricks are made from natural resources that form clay from elements of soil and additives. In general, red bricks are made from the protective topsoil of Earth. The process of brick-making is by taking away from the natural resources and depleting minerals from nature.
Furthermore, following this realization, cement blocks have been appreciated as an alternative to help the environment. The production of cement blocks do not take away from the resources and have been much appreciated for reducing our footprint and impact on natural resources.
But not all bricks (red) are harmful and stolen from the environment. The Fly Ash Bricks or AAC blocks industry soon followed easy plant set ups of both without harming the environment.
As for cement blocks, before you decide they are the environment’s most friendly material, you might want to reconsider. As all the other characteristics, bricks and blocks both have their perks in the environmental impact.
A Win for the Bricks
To some builder’s arguments, bricks are considered environmentally friendly building materials.
One main reason to support this argument is the brick’s recyclability. Red bricks are actually made from Earth materials that can be recycled. This means that they can be recycled back to Earth for natural landfills. Although blocks are generally more environmentally friendly to make, they are not as recyclable as bricks.
Although you may not be considering the day of your new project building coming down, as you are preparing to build a new structure, this could also impact your future renovations. The concrete blocks that are demolished during demolition just adds to waste and cannot be reused.
Buildings built on blocks will lead to heaps of waste when broken down, which does not help to the piling heaps of waste we struggle with already. In comparison to buildings and structures built out of brick, blocks tend to have a negative impact on the environment in the future.
A win for the Blocks
As mentioned before, blocks are a great choice to consider when thinking about the process that blocks and bricks are made in. In general, blocks do not take away from our Mother Earth, and therefore does not harm nor deplete nature.
In fact, blocks are made from waste. Although they cannot be recycled themselves, they can be made from recycled material. When blocks are made from Fly Ash, they are just an end product of the residue left from power plants.
With our concerns of the environment, this type of approach to make building materials are hoped to be further branched into building with “green” materials.
These are features that are not key elements to compare brick and cement blocks but still features you may want to consider for your project.
Since bricks have a tendency to expand with time for the first few years of its life, it is important to consider expansion joints when using bricks. This means a careful condition of the structural integrity and flexibility overall.
Blocks on the other hand are commonly used as partitions in exterior and interior applications.
If you are considering layering a coat of paint on the surface, whether it is now or in the future renovations, you may want to consider the two materials again.
Applying paint on the surface can be a different experience for the two materials. For concrete materials, the composition easily accepts the paint while bricks tend to cause paint to peel off.
This is due to elements that are diffusing out of the bricks after it is made.
Blocks are lighter in weight than bricks. This provides workability, flexibility, and durability. This provides a dry density ratio which is favored for modern construction.
Do keep in mind, these are in reference to the overall dimension of the cement block or brick. As for cement blocks that have lots of air-entrainment, it could be much lighter. An 8-inch concrete can weigh up to 43 pounds while a clay brick could weigh close to 5 pounds.
If you favor the lightweight feature of the concrete block, you may want to look at autoclaved aerated concrete. These are specifically aimed for lightweight features by mixing more air into the unit. They can weigh up to 80% less than traditional blocks.
Of course, it comes with a cost and it’s a literal cost. Some aerated blocks can be double the price of a traditional cement block.
Application of blocks have generally “thinner” building walls which help with saving space. If you are challenged with a small lot in a big space, few inches that you can gain by using block could go a long way.
Blocks are available in larger sizes than most bricks therefore they are a quicker alternative in building.
Climates and Natural Disasters
Generally, concrete blocks are known to be a great building material in areas with earthquakes. Due to its high durability in natural disasters, they are recommended by many countries that suffer natural hazards often or at high levels.
(Source: Turn bull masonry)
Now let’s consider an example of comparing brick and block when building a home. This is an overview that you could consider if you are building a house, for example, but it will still depend on your project and should only be considered as a general guide.
|Great for homes in hot regions that need heat absorbed by brick.||Great for areas prone to hurricanes and earthquakes (Natural Disasters)|
|Recyclable||Great for sound-proofing in busy and loud cities.|
|High fire-resistance||Cheaper to build|
|High durability||Made from recycled materials|
Source on concrete vs. block
Overview of Brick vs. Block
Generally speaking, the optimum cement block or brick would be a hollow unit without compromising any mechanical features of a regular unit that has high compressive strength.
The best option would offer potential energy savings, decreased raw material usage, and a recyclable material. Yet, the two building units both fight for these features, and depending on your project and preference, your choice will change. Therefore, neither building unit can be said is better than the other.
If you are here to decide which material to use, it’s a great way to start by going through each characteristic and considering what is more important to you in each section, then determining which building unit you will choose in the end. Of course, you also have the option of using the two in combination in order to take advantage of their respective strengths.
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